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Dose criteria for emergencies

  • Dose criteria for emergencies indicate what civil protection measures should be taken above a certain level of expected radiation exposure to humans in the event of a radiological emergency.
  • For the protective measure "Sheltering" or, respectively, "Evacuation", the dose criterion is an effective dose of 10 and, resp., 100 millisievert within 7 days.
  • For the protective measure "Intake of iodine tablets", the dose criterion is an organ-specific dose of the thyroid of 50 millisievert for children up to age 18 and pregnant women and, resp., 250 millisievert for persons between age 18 and age 45 within 7 days.

Shoes in front of a line

In order to be able to act quickly and appropriately in the event of a radiological emergency, it is necessary to determine in advance, above which certain level of expected radiation exposure to man measures should be taken. That is the reason why "dose criteria for emergencies" have been established; these are values where measures are taken in case they are exceeded, so that people and the environment are exposed to as little radiation as possible in a radiological emergency. These dose values have been laid down in the so-called "Ordinance Containing Dose Criteria for Emergencies".

The dose of radiation serves as valuation standard. It states how much radiation a person – in relation to its mass – has taken up. Thus, the dose criteria for emergencies are dose values; they are given in the unit millisievert (mSv).

Dose values can be estimated through prognoses prior to or during a release of radioactivity. For this purpose, the BfS operates the decision support system RODOS. If radioactivity is already released, current radiological environmental measurement data and measurements of people who have been exposed to radiation can make the dose values more precise.

Why are dose criteria for emergencies needed?

In the event of a radiological emergency different civil protection measures can be taken:

Fixed dose criteria for emergencies indicate from when which measure is to be carried out for radiation protection reasons. The dose type is also important for different civil protection measures:

  • For the administration of iodine tablets, solely the organ dose of the thyroid is relevant. That is the dose which only affects the thyroid. In order for the thyroid to not be able to take up radioactive iodine in the event of a radiological emergency, high-dose iodine tablets should saturate the thyroid with non-radioactive iodine beforehand. The dose criteria for emergencies for this measure is thus an organ dose for the thyroid.
  • The effective dose is taken as a measure for "Evacuation" and "Sheltering". The effective dose is the sum of all organ doses. It describes the effect of the radiation on the whole body.

Dose criteria for emergencies serve as a measure for the justification of certain measures from the radiation protection point of view. However, when taking a decision about such measures, further aspects must be taken into account, e.g. whether the measure is feasible and what additional risks may come from it (e.g. the evacuation of hospitals). Exceeding a dose criteria for emergencies does not automatically trigger a measure.

If the dose levels are below the respective dose criteria for emergencies, civil protection measures must be discussed with regard to proportionality. In any case, the radiation exposure to the public should be kept as low as reasonably achievable.

Overview of dose criteria for emergencies

MeasureOrgan-specific dose (thyroid)Effektive doseIntegration time and exposure pathways
Sheltering 10 millisievertExternal exposure in 7 days and committed effective dose due to radionuclides inhaled during this period
Intake of iodine tablets

50 millisievert (children up to age 18 as well as pregnant women)

250 millisievert (persons between age 18 and 45)

Radioiodine inhaled over a period of 7 days including the committed equivalent dose
Evacuation100 millisievert External exposure in 7 days and committed effective dose due to radionuclides inhaled during this period

Civil protection measures

Civil protection measures

Measures "Sheltering" and "Evacuation"

For the civil protection measures "Sheltering", the dose criterion of emergencies is an effective dose of 10 millisievert; for the civil protection measure "Evacuation" the dose criterion of emergencies is an effective dose of 100 millisievert. This effective dose is composed of

  • The dose an adult person would receive when it would permanently stay outdoors for seven days during the accident: In this case both the radiation from the outside ("external exposure") and the radiation from inhaled radioactive particles ("internal exposure") contributes to the total dose
  • And the dose this adult person would receive from the radiation emitted by the radioactive particles over the following months and years, which was taken up by the body during these seven days via breathing air and would not have been exhaled immediately (committed effective dose). Some radioactive particles remain inside the body for a short time only and are quickly removed by the metabolism, others are built into the bones where they remain until they decay. Depending on the half-life of the respective radionuclide, seconds to decades pass until decay.

Intake of iodine tablets

Measure "Intake of iodine tablets"

For the civil protection measures "Intake of iodine tablets" the dose criteria for emergencies for children up to age 18 and pregnant women is an organ-specific dose of the thyroid of 50 millisievert, for adults between age 18 and 45 an organ dose of the thyroid of 250 millisievert. The organ dose is composed of

  • The dose of radioactive iodine (radioiodine) individuals would inhale when staying outdoors permanently for 7 days during the release
  • And the dose that would result from the radiation of the iodine deposited in the thyroid in the following 3 months (the dominant long-living radionuclide iodine I-131 has a half-life of 8 days and has nearly completely decayed (99.9 %) after 80 days).

Persons over age 45 should not take iodine tablets, since metabolism dysfunctions of the thyroid occur more frequently with increasing age. That increases the risk of side effects of an iodine blockade. Furthermore, the probability to develop thyroid cancer caused by ionising radiation decreases with increasing age.

State of 2022.12.22

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